Calling nextScene of movie loaded on mclip

I need a button fwd and other backward to command a loaded movie, using scenes.

Button FWD should tell a movie loaded in: _root.myclip to go the next scene
and Button BKW should tell a movie loaded in: _root.myclip to go the previous scene

It seems that calling scenes in mclips is difficult. Can’t invoke it’s names because different movies with different amount of scenes will load into _root.myclip

Any help?